#app {
  width: 7.5rem;
  height: 100vh;
  border: 1px solid black;
  margin: 0 auto;
  position: relative;
}
#app ul {
  position: absolute;
  bottom: 0;
  height: 0.9rem;
  border-top: 1px solid #ddd;
  width: 100%;
}
#app ul li {
  float: left;
  width: 25%;
  font-size: 0.24rem;
  position: relative;
  height: 100%;
  cursor: pointer;
}
#app ul li.active {
  color: red;
  background-color: rgba(221, 221, 221, 0.555);
}
#app ul li .item {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
#app ul li .item .icon {
  font-size: 0.3rem;
  text-align: center;
}
#app ul li .item .text {
  text-align: center;
}
